The present invention is directed to a composition which may be employed to remove scale. More particularly, the composition includes an anionic surfactant, a nonionic surfactant, an ethanolamine, zinc and hydroxyacetic acid.
Scale is a general term to describe precipitates from aqueous fluids which deposit on surfaces, general (a) a result of water evaporation. Scale mterials include compounds such as sulfates, oxides, carbonates, halides and the like of metals such as iron, calcium, magnesium and potasssium. Examples include calcium carbonate and iron oxides. Scale can also result from deposition of organic material such as grease and oil present in the aqueous medium.
To be effective, a descaling composition should break down all of the components of scale. Primarily, the descaling composition should remove carbonates and sulfates from the surface to be cleaned. In certain instances the ability to remove grease and oil is an important property.
A number of methods have been devised to prevent or remove scale. For example, Rubin, in U.S. Pat. No. 3,075,924 teaches a detergent composition which includes a long chain aliphatic sulfate and an alkyl amine acetic acid. The mixture serves as a chelating agent to complex with metal irons.
Clark et al, in U.S. Pat. No. 3,053,897, discloses compositions for the removal of rust and scale. As previously discussed, rust may be considered a form of scale when the iron oxide is deposited by an aqueous mixture. Clark teaches the use of triethanolamine in combination with an alkali and an aliphatic hydroxy acid. Clark also teaches the use of alkali metal salts of sulfonated fatty acids.
Conklin et al, in U.S. Pat. No. 2,847,384, discloses a descalin composition which includes a nonionic wetting agent which is a mixture of polyoxythylene-propylene polymeric compounds with sodium xylyene sulfate.
Petroy, U.S. Pat. No. 3,699,047, employed zinc ion in a scale inhibiting composition which may also include an alkylene amine acetic acid compound.
Monson, in U.S. Pat. No. 2,589,195, discloses an inhibiting scale composition which includes a triethanolamine which is reacted with an ethylene oxide to form an amine having a number of ethylene oxide units. The terminal hydroxy groups are acylated with a fatty acid.
However, there is a continuing need for a descaling composition which can remove scale deposited from fresh or brine water from all types of surfaces and is relatively safe, easy to use, and effective.